Logical Reasoning

PT133 · S3 · Q21 Chemist: The molecules

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Chemist: The molecules of a certain weed-killer are always present in two forms, one the mirror image of the other.

Conclusion

Much of the data on the effects of this weed-killer are probably misleading.

Evidence

Because the weed-killer has two different forms of molecule (one that kills weeds, one that does nothing), the weed-killer can be very effective or not at all effective depending on local soil conditions, since those determine whether the killer form or the non-killer form of the molecule ends up being more concentrated in the soil.

Evaluation

The new guy in the conclusion is . What is the author assuming about much of the data, that would make it misleading?

It sounds like he's saying, / vice versa where the data is based on soil where the non-killer molecule would be predominant, in which case the weed-killer would look weaker than it should.

Goal

If the weed-killer has been tested on a wide variety of local soil conditions, then we should have a pretty accurate sense of how it performs on average. But if it's only been tested on a narrow variety of local soil conditions, then the data might mislead by making it seem more widely effective or ineffective (depending on which narrow type of soil we studied) than it really is.

21.

Which one of the following, if true, most strengthens the chemist's argument?

  1. In general, if the molecules

    No Impact On Conclusion

    This tells us nothing about where any of our data on the effectiveness comes from, whether they studied a wide or narrow range of local soil conditions.

    4% picked this

  2. Correct

    Almost all of the data

    Why this is right

    This addresses our new guy "the data" head-on. It sounds like this weed-killer has been tested in artificial lab conditions, in which neither molecule is the predominant one. We learned that local soil conditions will usually favor the breakdown of one form of molecule or the other, leaving the remaining one as the dominant one that's more concentrated in the soil. If most of the time actual soil is imbalanced (there's either more of form 1 or form 2), but almost all the data is based on lab soil that is equally form 1 and form 2, then this would support the idea that our data is probably giving us a misleading sense of how effective the weed killer will be in actual conditions.

    Skill tested: Strengthen · how this choice captures the argument's function is the move to repeat next time.

    62% picked this

  3. Of the two forms of

    Unclear Impact

    Without knowing whether the data we have for this weed killer was based on soil where the killer form is present or soil where the non-killer form is present, we can't tell whether this is misleading. If most of our testing data was on soil where the killer-form is more concentrated, then our data should match up with reality most of the time. If most of our testing data was on soil where the non-killer form is more concentrated, then our data is probably misleading.

    6% picked this

  4. The data on the effects

    Opposite

    This would weaken the argument and make our data sound pretty trustworthy, since it takes into account the variety of soil conditions.

    13% picked this

  5. Data on the weed-killer's effects

    Unclear Impact

    This discusses a certain scenario under which we would receive misleading data (if the data is based on examining only one of the two forms of molecule). But we don't know if "much of the data" is examining only one of two forms, so this answer doesn't seem useful until we know whether any of the data has actually been compiled by studying solely one form.

    15% picked this

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